This invention relates to analog controls, and, more particularly, to controls for facilitating movement of work platforms and the like.
Aerial work platforms have been developed and in use for more than twenty five years. Their primary purpose is to raise workers quickly and safely to positions to do necessary work. They replace earlier means of access such as ladders and scaffolds. Some models can also reach below a surface or a long horizontal distance from the surface on which they are located, and some types of lifts can place workers as high as 150 to 250 feet above the ground.
Three types make up the major population of such machines:
1. Vehicle-Mounted Elevating and Rotating Aerial Devices as covered by ANSI/SIA A92.2xe2x80x941990. These machines are typically mounted on a commercial truck chassis but may be mounted on a trailer chassis and are used in erection and maintenance of utility lines. They include models where the work platform is supported by an articulating or a telescoping boom which is mounted on a turntable that can rotate about an axis.
2. Boom-Supported Elevating Work Platforms as defined in ANSI/SIA A92.5xe2x80x941992. These machines are self-propelled, typically have a telescoping and/or articulating boom and are used in construction and maintenance tasks.
3. Self-Propelled Elevating Work Platforms as defined in ANSI/SIA A92.6xe2x80x941990. These machines (typically scissor-lifts) elevate the work platform vertically but do not position the platform horizontally completely outside the base on which it is supported. They are also used in general construction and maintenance tasks.
4. Other aerial work platforms on which the analog control maybe utilized include: Manually Propelled Elevating Work Platforms as defined in ANSI/SIA A92.3xe2x80x941990. These machines are manually propelled and have platforms that cannot be positioned completely outside the base.
5. Airline Ground Support Vehicle-Mounted Vertical Lift Devices as defined in ANSI/SIA A92.7xe2x80x941990. These are machines designed specifically for aircraft servicing and maintenance.
6. Vehicle-Mounted Bridge Inspection and Maintenance Devices as defined in ANSI/SIA A92.8xe2x80x941993. These machines are designed to reach out, down and under a bridge for inspection and maintenance.
7. Mast-Climbing Work Platforms as defined in ANSI/SIA A92.9xe2x80x941993. These machines are designed to place several workers on a platform along a wall or similar vertical surface to do extensive operations.
Controls for operating most of the types of aerial platforms mentioned above are comprised of electrical switches or other devices mounted at an operator""s station on the platform. These electrical devices control valves or other means on the chassis which in turn activate hydraulic or electrically powered devices such as cylinders or motors. Mechanical controls are difficult or impossible to use for controls on the platform because of the distance from the platform to the chassis and the mechanical positioning of the platform relative to the chassis in order to reach the desired work location. Likewise, it is difficult and inefficient, except in the simplest machines, to route multiple hydraulic lines with hoses at mechanical joints up to the platform where hydraulic valves could be used to control machine motions. Therefore, the industry practice has evolved to the use of electrical switches and controllers on the platform which actuate hydraulic or electrical means on the chassis to cause the desired motion.
Two general types of electrical devices are (1) the simple on/off switch that may be actuated in two directions, e.g., up or down, and usually is spring loaded to return to neutral, and (2) the controller type of switch that usually provides an electrical output signal proportional to the displacement of the handle of the controller. The proportional controller is important to the operator and is used to make smooth starts and stops and to move at a reduced rate of speed as existing conditions may make desirable. Proportional controllers are used on most sophisticated aerial work platforms and on those providing greater platform height. The two types are used interchangeably in this document and it will be understood that the word xe2x80x9cswitchxe2x80x9d is to be interpreted broadly and includes a controller, and vice versa.
Switches were typically located on the operator""s control panel in patterns which may have been influenced by aesthetics, space considerations and fabrication economy. Beginning in 1980, the applicable consensus standard for boom-supported elevating platforms (ANSI A92.5xe2x80x941980) specified that xe2x80x9call directional controls shall move in the direction of the function which they control when possible, and shall be of the type which return to the xe2x80x98offxe2x80x99 or the neutral position when released. Such controls shall be protected against inadvertent operation.xe2x80x9d Directional controls are defined in the ANSI A92.5xe2x80x941980 Standard as xe2x80x9call controls necessary to raise, lower, rotate, telescope, drive or otherwise initiate the powered functions of the work platform.xe2x80x9d A similar requirement had first appeared in the ANSI A92.6xe2x80x941979 Standard on Self-propelled Elevating Work Platforms, albeit without the definition of xe2x80x9cdirectional controls.xe2x80x9d
One design with clear advantages with respect to earlier control arrangements is disclosed and described in U.S. Pat. No. 4,331,215xe2x80x94Grove et al. This patent discloses controls that are individual electric devices mounted on a surface slightly inclined to the vertical or on a second surface slightly inclined to the horizontal. This arrangement permits all of the controls to operate in substantially the same direction in which the platform moves as a result of the control activation. This design meets the requirement of the applicable consensus standard (ANSI A92.5xe2x80x941992) and provides an approach that minimizes operator error, a major cause of accidents on aerial work platforms.
As noted in the Grove et al. Patent, workers such as electricians, painters, sandblasting operators, bricklayers and carpenters using these machines are skilled primarily in the area of their work specialty and the aerial platform they are using serves solely as a positioning means, hence, many operators do not become as proficient as the trained operators of cranes or earth-moving machinery who do nothing but operate such machines full time. Moreover, operators of aerial platforms may use one machine for a few days and may then be assigned a different make and model that has a different control arrangement, or may even rent different machines for use on an xe2x80x9cas neededxe2x80x9d basis. Although operators of aerial platforms are required to be trained, such training may be limited and often does not include specific training on the control variations used on different makes and models. Therefore, the opportunity for inadvertent errors is increased by the requirement for the operator to first select the proper control, second, to check to be certain of which way to operate the control handle, and third, to then implement the control operation.
Other machines utilize controls which differ from the typical steering wheel, accelerators brake, and gear shift with which most people are familiar. Various construction vehicles such as skid-steer loaders, bulldozers, and front end loaders are provided with control levers usually based on the mechanical devices which effect the motion but often do not move in a direction of the motion caused nor do they provide a simulated model of the machine for quick operator recognition and orientation. Certain models of power lawn mowers currently available also utilize levers to effect driving and steering but lack the analogous motion and the simulated model of the machine for quick operator recognition and orientation. Another control layout which was developed on early aircraft and is still used on certain light aircraft and military fighters is the pilot""s cockpit control stick. When the control stick is pushed to the left, the aircraft rolls to the left in response; when the stick is pushed forward, the aircraft rotates nose downward in response. However, the control stick does not provide the third axis control for the rudder, and, most importantly, does not provide the simulated model which ensures the quick recognition and orientation needed for aerial platform operators. Pilots are required to be trained and licensed, even for light civilian aircraft, while military aircraft can only be flown by pilots who have hundreds of hours of training and flight experience. On the other hand, training of aerial platform operators is often minimal; indeed, a worker at a large construction site will often come upon an aerial platform not in use, will start it if possible, and will proceed to use it without permission or any training.
Further requirements for the operator""s controls are specified in the ANSI/SIA A92.6xe2x80x941990 Standard for Self-propelled Elevating Work Platforms that require that the upper controls (on the platform) shall xe2x80x9cinclude a control which shall be continuously activated in order for upper directional controls to be operational and which automatically returns to the off position when released.xe2x80x9d A similar requirement is specified in the ANSI/SIA A92.5xe2x80x941992 Standard for Boom-Supported Elevating Work Platforms by specifying that the upper controls provided at the platform shall xe2x80x9cinclude a separate safety control which shall be continuously activated for upper directional controls to be operational, and which renders upper directional controls inoperative when released.xe2x80x9d These requirements have typically been met by having a separate foot pedal or an equivalent switch that must be operated by the operator in order for the directional controls to be used. A foot pedal can be actuated by the operator while using one hand to operate the directional control. However, in addition to the cost and installation expense, the foot pedal requires an electrical cord connection which must be durable, and together with the pedal is subject to rough service, deterioration due to weather conditions and damage from falling objects. A separate hand switch may be utilized but the operator may then be required to use both hands. A safety control may be integrated into each directional control but this would require three or more duplicate safety switches, with the controls of each capable of being released by the operator if he or his hand is trapped such that he cannot return the directional control to neutral.
In general, a safety control, in order to be most effective and provide maximum safety enhancement, must meet at least the following requirements:
1. It must prevent inadvertent operation of a directional control in case the directional control is struck by the operator, by other personnel or by a falling object or tool being used in performance of a work task;
2. When released it would preferably provide a signal to stop all powered functions if a malfunction occurs in the directional control or any other component of the control system;
3. When released it would preferably provide a signal to stop all powered functions if a malfunction occurs in any component of the power supply system; and
4. It would preferably provide a signal to stop or prevent unsafe powered motion that may be caused by a single point failure mode, which is an event caused by malfunction of a single component. It is to be avoided in aerial work platforms because of the potentially dangerous motion of the platform where the operator is located.
Thus, despite the advances made in the art, the control systems and arrangements discussed above are deficient in not providing a total human factors solution and in not utilizing a control configuration and mechanism that can provide rapid and certain recognition and orientation to both trained and untrained operators, resulting in increased safety and operator efficiency.
A control system is provided that may enhance recognition by the operator in that portions of the control system correspond to portions of the mobile machine that is to be controlled and that may enhance comprehension by the operator in that movement of portions of the control system produce like movements in the corresponding mobile machine portions. The control system may be designed according to the following guidelines. First, the mechanisms of the control may be approximately parallel to those of the overall machine. Second, the motions of the control may cause motions of the machine mechanisms in the same direction that the control is moved. Third, the operator can observe the motions of the control and visually verify that the machine is responding with the intended motion. Any or all of these principles may be employed by the control systems disclosed herein.
According to the present invention, a control system for providing signals in response to an operator""s input is provided. The control system includes a fixed base, a handgrip, a first pivotable portion, a second pivotable portion, and a telescoping portion. The first pivotable portion is pivotable about a substantially vertical axis, the second pivotable portion is pivotable about a substantially horizontal axis. The second pivotable is coupled to the first pivotable portion. The translating portion is slideable along an axis that is substantially horizontal. The handgrip is operatively coupled to the telescoping portion.
The control system may also include three switches or switch systems to sense motion or urging of each of the three movable portions. A first switch or switch system is disposed proximate to the first pivotable portion for sensing clockwise or counterclockwise urging of the handgrip by the operator. A second switch or switch system is disposed proximate to the second pivotable portion for sensing up or down urging of the handgrip by the operator. A third switch is disposed proximate the telescoping portion for sensing inward or outward urging of the handgrip by the operator. Thus, the handgrip is capable of being urged in an up or down motion, a clockwise or counterclockwise motion, and an inward or outward motion to impart corresponding output signals thereby. Each of these motions may be imparted simultaneously, and therefore sensed and controlled simultaneously. Any type of switches may be employed, such as limit-type switch or pair of opposing switches, including proximity switches, non-contact type switches, controller-type switches that produce a proportionate output, and the like.
Preferably, the first pivotable portion includes a body that pivots on a substantially vertical axis. The first pivotable portion supports a substantially horizontal pin about which the second pivotable portion may pivot. The telescoping portion preferably includes an outer boom that is coupled to the first pivotable portion and extends outwardly from the pivot assembly. An inner boom extends from the outer boom and is slideable therein. The handle or handgrip is coupled to the inner boom such that movement of the handgrip may move any one or combination of the three movable portions of the control.
The first pivotable portion may be visible from outside the control system as a cylindrical body, and therefore simulates the structure of a rotatable turntable or turret of a mobile machine. The first pivotable portion may be shaped in other configurations to match the shape of the turret of the particular machine on which the control system may be employed. The second pivotable portion may (optionally) be visible from outside the control system. The pivotable portion simulates a joint of an aerial work platform, and/or provides an effective means for providing for up and down motion of the control. The telescoping portion, especially the inner boom, preferably is visible from outside the control system, and simulates the telescoping portion of the mobile machine. In this regard, the switches provide signals such that the mechanisms of the mobile machine (that is, for example, the turret, articulating or elevating joint(s), and telescoping boom) rotate and/or telescope in the same direction that the corresponding structure of the control system is urged.
According to another aspect of the present invention, a control for operating a mobile machine includes a structure having movable members that simulate and correspond to the mechanisms of the mobile machine. The movable members are capable of movements by the operator that impart corresponding motions to the corresponding mechanisms of the mobile machine. The structure is capable of being structurally mounted to the platform at an operator station that is disposed on the platform.
At least three bi-directional motion controls are provided that each operate one of two separate sensors when the control is moved in one of two opposite directions. The motion controls thus provide for motion of the corresponding mechanisms of the mobile machine in the opposing directions, such that the mobile machine undergoes motions that correspond to movements imparted to the control by the operator whereby recognition and comprehension by the operator is expedited and enhanced. The three bi-directional controls preferably are incorporated within the analog control in a single unit.
Preferably, springs are coupled to each one of the three moveable portions of the control so as to urge each one of the moveable portions to its neutral state, at which the switches are disengaged. Each of the switches may be a bi-directional switch such that motion of the control may be sensed in either a positive or negative direction (that is, clockwise or counterclockwise, up or down, or retract and extend, respectively). A safety switch and/or trigger may be included to provide lock out, driving, and numerous other safety and operational functions.
The handle or handgrip of the present invention may also be capable of pivoting clockwise or counterclockwise relative to the control boom to which it is attached. Devices within the control, such as within the boom structure, move in response to pivoting of the handle. Switches sense the movement of these devices and provide a signal for control of a portion of the mobile machine. Pivoting the handgrip for an added control is suitable for a crane that includes both a main boom and a jib boom. Further, the handle or handgrip may be disposed in various orientations, including, for example, pointing upward and away from the movable portions of the control such that a cover of the control serves as an operator arm rest. The orientation of the handle may be chosen according to the most advantageous direction that the operator may face with respect to the particular machine on which the control is employed.
According to another aspect of the present invention, the mobile machine comprises an aerial work platform, having a chassis, an elevating mechanism and an operator platform. The operator platform having a control device for controlling the aerial work platform. The control device includes a fixed portion, a first pivotable portion, a control pivotable boom, a handle or handgrip, and at least one switch system.
The fixed portion is secured to the operator platform, and the first pivotable portion is pivotable on the fixed portion upon clockwise and counterclockwise urging by the operator. The control boom includes a control inner boom that is inwardly and outwardly urgeable along a longitudinal axis of the control boom. A first end of the control boom is coupled to the handle and a second end is coupled to the first pivotable portion. The control system includes a pair of switches. A first switch system is disposed (that is, has an operative component on) a moveable portion of the pivotable portion and is activated by the motion of the pivotable portion upon urging by the operator. A second switch system is disposed on a moveable portion of the control boom and is activated by the motion of the control boom upon urging by the operator. A third switch system is disposed on the control boom and is activated by the motion of the telescoping portion of the boom upon urging by the operator. The first, second, and third switch systems enable signals whereby the aerial work platform may be controlled. Also, a portion of the control device enhances comprehension of the operation of the aerial work platform by the operator. Thus, the control may consist of three bi-directional controls according to an aspect of the present invention. However, the control may also include additional bi-directional controls, as required.
According to another aspect of the present invention, a mobile machine having a chassis and a power system for providing power to components of the mobile machine is provided. The mechanisms of the mobile machine include a main boom mounted on a rotatable platform at a pivotable joint. The main boom is capable of telescoping inwardly and outwardly, elevating about the pivotable joint, and rotating on the rotatable platform. The mobile machine also includes a control device that is mounted on an operator platform for effecting telescoping motion of the boom. The control device includes a fixed portion, a first and a second pivotable portion, a control boom, and a handle or handgrip.
The fixed portion is secured to the operator platform. The first pivotable portion is pivotable on the fixed portion and is clockwise and counterclockwise urgeable relative thereto so as to provide a signal for corresponding clockwise and counterclockwise rotation of the rotating platform. The second pivotable portion is coupled to the first pivotable portion and is upwardly and downwardly pivotable relative to the first pivotable portion so as to provide a signal for corresponding upward and downward movement of the main boom about the pivotable joint. The control boom includes a control inner boom that is inwardly and outwardly urgeable along a longitudinal axis of the control boom so as to provide a signal for corresponding inward and outward telescoping of the main boom of the mobile machine. The control boom has a first end and a second end that is coupled to the pivotable portion. The handle is coupled to the first end of the control boom for imparting motion thereto by an operator. The control of the mobile machine includes switches for sensing movement of the moveable portions of the control.
The mobile machine may also include, according to another aspect of the present invention, a linkage coupling a support of the control device to the main boom or like structure of a moveable machine such that a movement of the main boom about the pivotable joint moves the control device in a corresponding direction (such as, for example, clockwise or counterclockwise). The mobile machine may also include a jib boom disposed at a distal end of the main boom. The control device may also include a simulated jib boom disposed at a distal end of the control boom, whereby the recognition of the structure of the main boom and jib boom is enhanced and comprehension of the function of the control device is enhanced. The control of the mobile machine may also include a mechanism for sensing pivoting of the handle to control the jib boom. The mobile machine may orient the control device such that each one of its pivotable portions are disposed at an end proximate the operator, thereby enhancing recognition and comprehension by the operator. In this regard, the operator can look ahead and downward and see the motion that he imparts to the control system while following motions of the boom at the same time.
Some embodiments of the control systems described herein provide a single control that includes the three primary boom motions: lift, swing, and telescope. Further, the three motions may be controlled by one hand (that is, by either hand) of the operator. This eliminates the time the operator uses to select a specific control and transfer his hand to that control, and provides other apparent advantages. Because the operator does not have to select a control, such as one of three or four primary control levers (that may be identical) as in prior control devices, the probability of error is reduced, among other advantages.
Preferably, the moveable portions of the control are simulated parts of the mobile machine in that they include many or most of the structure and functional aspects of the corresponding machines part. For example, the inner and outer booms or tubes described herein simulate the corresponding structure of the machine for which the control is designed. Upon initially encountering the control including the simulated booms or tubes, an operator will recognize that such structure corresponds to the structure of the machine, and will comprehend that extending or telescoping the inner boom outwardly relative to the outer boom will produce such a motion in the machine.
In this regard, the analog control as described herein provides greater efficiency for both cranes and aerial platforms and the operator, thereby realizing a significant cost advantage. It appears that it may provide a valuable safety improvement as compared to other control arrangements, among other advantages.